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ABSTRACT: The intact polar lipid (IPL) composition of twelve hydrothermal vent deposits from the Rainbow (RHF) and Lucky Strike hydrothermal fields (LSHF) has been investigated in order to assess its utility as a proxy for microbial community composition associated with deep-sea hydrothermal locations. Gene-based culture-independent surveys of the microbial populations of the same vent deposits have shown that microbial populations are different in the two locations and appear to be controlled by the geochemical and geological processes that drive hydrothermal circulation. Large differences in the IPL composition between these two sites are evident. In the ultramafic-hosted RHF, mainly archaeal-IPLs were identified, including those known to be produced by hyperthermophilic Euryarchaeota. More specifically, polyglycosyl derivatives of archaeol and macrocyclic archaeol indicate the presence of hyperthermophilic methanogenic archaea in the vent deposits, which are related to members of the Methanocaldococcaceae or Methanococcaceae. In contrast, bacterial IPLs dominate IPL distributions from LSHF, suggesting that bacteria are more predominant at LSHF than at RHF. Bacterial Diacyl glycerol (DAG) IPLs containing phosphocholine, phosphoethanolamine or phosphoglycerol head groups were identified at both vent fields. In some vent deposits from LSHF ornithine lipids and IPLs containing phosphoaminopentanetetrol head groups were also observed. By comparison with previously characterized bacterial communities at the sites, it is likely the DAG-IPLs observed derive from Epsilon- and Gammaproteobacteria. Variation in the relative amounts of archaeal versus bacterial IPLs appears to indicate differences in the microbial community between vent sites. Overall, IPL distributions appear to be consistent with gene-based surveys.
Geobiology 01/2013; 11(1):72-85. · 4.11 Impact Factor
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ABSTRACT: The Eocene-Oligocene transition (EOT; ca. 33–34 Ma) was a time of pronounced climatic change, marked by the establishment of continental-scale Antarctic ice sheets. The timing and extent of temperature change associated with the EOT is controversial. Here we present multiproxy EOT climate records (~15–34 k.y. resolution) from St. Stephens Quarry, Alabama, USA, derived from foraminiferal Mg/Ca, d18O, and TEX86. We constrain sea-surface temperatures (SSTs) in the latest Eocene and early Oligocene and address the issue of climatic cooling during the EOT. Paleotemperatures derived from planktic foraminifera Mg/Ca and TEX86 are remarkably consistent and indicate late Eocene subtropical SSTs of >28 °C. There was substantial and accelerated cooling of SSTs (3–4 °C) through the latest Eocene “precursor” d18O shift (EOT-1), prior to Oligocene Isotope-1 (Oi-1). Our multispecies planktic foraminiferal
d18O records diverge at the E/O boundary (33.7 Ma), signifying enhanced seasonality in the earliest Oligocene in the Gulf of Mexico.
Geology 02/2012; 40(2):159-162. · 3.61 Impact Factor
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ABSTRACT: Although commonly reported in marine and freshwater environments, little is known about the biological sources of long chain alkyl 1,13- and 1,15-diols, and factors controlling their distributions. Here we analyzed the occurrence and distribution of these lipids in a comprehensive set of marine surface sediments and compare their distributions with environmental conditions like sea surface temperature (SST), salinity and nutrient concentrations. Fractional abundances of the C28 1,13-, C30 1,13- and C30 1,15-diols show a strong correlation with SST and based on these results, we propose the Long chain Diol Index (LDI), which expresses the C30 1,15-diol abundance relative to those of C28 1,13-, C30 1,13- and C30 1,15-diols. The LDI shows a strong linear correlation with SST (LDI = 0.033 +ù SST + 0.095; R2 = 0.969, n = 162) over a temperature range of
Geochimica et Cosmochimica Acta 01/2012; 84:204-216. · 4.26 Impact Factor
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ABSTRACT: Ladderane fatty acids are commonly used as biomarkers for bacteria involved in anaerobic ammonium oxidation (anammox). These lipids have been experimen-tally shown to undergo aerobic microbial degradation to form short chain ladderane fatty acids. However, nothing is known of the production or the distribution of these oxic biodegra-dation products in the natural environment. In this study, we analysed marine water column particulate matter and sedi-ment from three different oceanic regimes for the presence of ladderane oxidation products (C 14 ladderane fatty acids) and of original ladderane fatty acids (C 18 and C 20 ladderane fatty acids). We found that ladderane oxidation products, i.e. C 14 ladderane fatty acids, are already produced within the water column of the Arabian Sea oxygen minimum zone (OMZ) and thus only low amounts of oxygen (< 3 µM) are needed for the β-oxidation of original ladderane fatty acids to pro-ceed. However, no short chain ladderane fatty acids were de-tected in the Cariaco Basin water column, where oxygen con-centrations were below detection limit, suggesting that the β-oxidation pathway is inhibited by the absence of molec-ular oxygen, or that the microbes performing the degrada-tion are not proliferating under these conditions. Compar-ison of distributions of ladderane fatty acids indicates that short chain ladderane fatty acids are mostly produced in the water column and at the sediment surface, before being pre-served deeper in the sediments. Short chain ladderane fatty acids were abundant in Arabian Sea and Peru Margin sed-iments (ODP Leg 201), often in higher concentrations than the original ladderane fatty acids. In a sediment core taken from within the Arabian Sea OMZ, short chain ladderanes made up more than 90 % of the total ladderanes at depths greater than 5 cm below sea floor. We also found short chain ladderanes in higher concentrations in hydrolysed sediment residues compared to those freely occurring in lipid extracts, suggesting that they had become bound to the sediment ma-trix. Furthermore, these matrix-bound short chain ladderanes were found at greater sediment depths than short chain lad-deranes in the lipid extract, suggesting that binding to the sediment matrix aids the preservation of these lipids. Though sedimentary degradation of short chain ladderane fatty acids did occur, it appeared to be at a slower rate than that of the original ladderane fatty acids, and short chain ladder-ane fatty acids were found in sediments from the Late Pleis-tocene (∼ 100 kyr). Together these results suggest that the oxic degradation products of ladderane fatty acids may be suitable biomarkers for past anammox activity in OMZs.
Biogeosciences 01/2012; 9:2407-2418. · 3.86 Impact Factor
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ABSTRACT: The diazotrophic community in microbial mats growing along the shore of the North Sea barrier island Schiermonnikoog (The Netherlands) was studied using microscopy, lipid biomarkers, stable carbon (δ(13) C(TOC) ) and nitrogen (δ(15) N) isotopes as well as by constructing and analyzing 16S rRNA gene libraries. Depending on their position on the littoral gradient, two types of mats were identified, which showed distinct differences regarding the structure, development and composition of the microbial community. Intertidal microbial mats showed a low species diversity with filamentous non-heterocystous Cyanobacteria providing the main mat structure. In contrast, supratidal microbial mats showed a distinct vertical zonation and a high degree of species diversity. Morphotypes of non-heterocystous Cyanobacteria were recognized as the main structural component in these mats. In addition, unicellular Cyanobacteria were frequently observed, whereas filamentous heterocystous Cyanobacteria occurred only in low numbers. Besides the apparent visual dominance of cyanobacterial morphotpyes, 16S rRNA gene libraries indicated that both microbial mat types also included members of the Proteobacteria and the Cytophaga-Flavobacterium-Bacteroides group as well as diatoms. Bulk δ(15) N isotopes of the microbial mats ranged from +6.1‰ in the lower intertidal to -1.2‰ in the supratidal zone, indicating a shift from predominantly nitrate utilization to nitrogen fixation along the littoral gradient. This conclusion was supported by the presence of heterocyst glycolipids, representing lipid biomarkers for nitrogen-fixing heterocystous Cyanobacteria, in supratidal but not in intertidal microbial mats. The availability of combined nitrogen species might thus be a key factor in controlling and regulating the distribution of the diazotrophic microbial community of Schiermonnikoog.
Geobiology 07/2011; 9(4):349-59. · 4.11 Impact Factor
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ABSTRACT: Long chain 1,14-diols have been reported in diatoms of the genus Proboscia and applied as specific biomarker lipids for such algae. We report here the presence of saturated C28, C30 and C32 1,14-diols in a culture of the marine heterokont alga Apedinella radians (Class Dictyochophyceae, order Pedinellales). Apedinella species occur globally, although predominantly in estuarine waters, so the finding has potential implications for the use of long chain 1,14-diols as biomarkers of Proboscia diatoms and as an indicator of upwelling
Organic Geochemistry 01/2011; 42(5):572-574. · 2.79 Impact Factor
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Limnology and oceanography 02/2010; 55(1):365-376. · 3.42 Impact Factor
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ABSTRACT: ABSTRACT Diatoms are important primary producers in present day Antarctic waters but their relative significance in the past is less clear. In this study we used long-chain diols to reconstruct Proboscia diatom productivity in shelf waters of the western Antarctic Peninsula over the last 8500 yr. Biomarker lipid analysis revealed the presence of a suite of long-chain diols in the sediments, mainly comprising the C28 and C30 1,14-diol isomers derived from Proboscia diatoms and C28 and C30 1,13-diols derived from other unknown algae. The relative importance of Proboscia diatoms was assessed using the relative abundances of 1,14-diols versus 1,13-diols, which showed that Proboscia diatoms were relatively more abundant during the Late Holocene, suggesting that stronger upwelling of circumpolar waters occurred at that time. The variations in the diol index strongly correlate with melt events in the Siple Dome ice core, suggesting that the climatic processes responsible for changes in mean summer temperature, open marine influence and atmospheric cyclonic activity recorded at Siple Dome, also controlled the productivity of Proboscia diatoms on the western Antarctic Peninsula region
Antarctic Science 01/2010; 22(01):3-10. · 1.56 Impact Factor
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CJ Hollis,
KW Taylor,
L Handley,
RD Pancost,
J Creech,
J Baker, S Schouten,
E Kennedy,
EM Crouch,
M Huber,
others
AGU Fall Meeting Abstracts. 01/2010; 1:04.
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ABSTRACT: In recent years, the idea of a rich microbial biosphere in the marine
sea floor has been widely accepted. This so-called “deep
biosphere” is estimated to contain ca. 50 % of Earth’s total
prokaryotic biomass with the overall order of magnitude of microbial
cells in the sea floor being the same as the biomass of all surface
plant life (Whitman et al. 1998). Evidence for the existence of a deep
biosphere comes, among others, from the analysis of intact polar lipids
(IPLs). This approach presumes that IPLs almost instantaneously lose
their polar head group after cell death and thus do not preserve on
geological timescales. Consequently, IPLs in the subsurface should
derive from in situ production and hence indicate the presence of living
prokaryotic cells. For example, in various oceanic subsurface sediments
archaeal IPLs have been found, suggesting that Archaea constitute a
major fraction of the deep biosphere biomass (Lipp et al. 2008). In this
study, we found IPLs of heterocystous cyanobacteria in a number of
ancient and deeply buried sediments. Heterocystous cyanobacteria are
strictly photoautotrophic organisms that are a common constituent of the
phytoplankton community in many freshwater and brackish environments but
are also encountered in the marine realm as endosymbionts of diatom
species. Under nitrogen-depleted conditions, these organisms carry out
nitrogen fixation in specialized cells, known as heterocysts. These
cells contain a suite of heterocyst glycolipids (HGs) that have not been
identified in any other organism and are thus unique biological markers
for nitrogen-fixing heterocystous cyanobacteria. Using high performance
liquid chromatography coupled to electrospray ionisation tandem mass
spectrometry (HPLC/ESI-MS/MS), we detected HGs in Pleistocene and
Pliocene Mediterranean sapropels buried up to 60 m below the seafloor.
In addition, these HGs were also found in lacustrine deposits of the
Oligocene Lake Enspel (35 Ma), the Eocene Lake Messel (47 Ma) and the
Eocene Green-River Formation (ca. 50 Ma). The presence of IPLs such as
HGs in these ancient sediments is remarkable, given the assumed lability
of IPLs with glycosidic or phosphoric head groups. Our data, however,
show that HGs with glycosidically bound head groups, unambiguously
derived from photoautotrophic organisms living in the photic zone of the
water column, can fossilize and be well preserved in the sedimentary
record. The presence of HGs in fossil sediments, thus, raises the
question whether certain IPLs, especially those with glycosidic head
groups, may be more recalcitrant than previously thought and can
constitute a significant fossil component of the so-called IPL fraction.
This has important consequences (1) for the use of IPLs as a proxy of
living prokaryotic biomass and (2) for the conclusion that Archaea are
the main standing stock of prokaryotes in the deep-biosphere.
AGU Fall Meeting Abstracts. 11/2009; -1:04.
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ABSTRACT: Albeit a relatively small community, Dutch scientists have been an
integral and active component of the various international drilling
programs (DSDP/ODP/ IODP and IMAGES), Interests in, and enthusiasm for
the program(s), also for the future, are strong. In this contribution,
we summarize ideas about the near future of European and global ocean
drilling from the Dutch perspective, as gathered from recent national
meetings of the community, and from the Netherlands IODP committee.
03/2009; 11:1326.
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ABSTRACT: Branched glycerol dialkyl glycerol tetraethers (GDGTs) containing 0 to 2
cyclopentyl moieties were initially detected in peat deposits [1].
Through the analysis of a global set of soils samples Weijers et al. [2]
showed that these GDGTs, probably of bacterial origin, are produced in
situ in these soils. Rivers and direct run-off transport these
compounds, together with other soil organic matter, to marine [3] and
lake sediments [4, 5]. Recently, Weijers et al. [6] defined two indices
that are based on branched GDGTs that are distinctively influenced by
two environmental factors. The cyclisation ratio of the branched
tetraethers (CBT) is related to soil pH and the methylation index of
branched tetraethers (MBT) is related to temperature and soil pH. Lake
sediments are often used for reconstructing past climatic changes. The
presence of branched GDGTs in lake sediments potentially allows
reconstruction of temperature and pH of the lake drainage area. We
performed organic geochemical analyses on a series of surface sediments
from 82 lakes characterised by variable amounts of soil organic matter
and from different geographical locations to establish the application
of the MBT/CBT as a continental palaeothermometer. Results show that in
all of the 82 lakes substantial amounts of branched GDGTs are present
(0.1-28% of total GDGTs). Besides the branched GDGTs crenarchaeol was
also found in appreciable amounts (on average 23% of the total GDGTs).
In the lakes from the northern hemisphere in fact the dominant GDGT is
crenarchaeol (38% of total GDGTs) followed by the pentamethylated
branched GDGT. In the southern hemisphere on the other hand we observe
the hexamethylated branched GDGT as the dominant GDGT and crenarchaeol
is here ten times less abundant then in the north (on average 3% of
total GDGTs only). The CBT, as defined by Weijers et al. [6], for the
entire data set ranges from values close to 0 (0.14 for Lake Ohrid) to
1.7 (Lake Nyos). The MBT ratio, also as defined by Weijers et al. [6],
for the sediments analyzed in this study varies between 0.09 (Lake
Bourget) and 0.91 (Brazil52). A strong linear correlation was found
between CBT and pH of the lakes in the northern hemisphere while in the
southern hemisphere there was no correlation between CBT and pH or CBT
and MAT. Mean annual air temperatures (MAT) and pH values were
calculated using the CBT and MBT values and the soil calibration from
Weijers et al. [6]. The temperatures calculated in this way were
considerably lower than the measured values. Moreover the MBT to
temperature correlation shows considerable scatter (r2 = 0.48). Still,
we observe that the lakes from high northern latitudes with lower
temperatures have overall lower MBT values compared to the ones at
southern lower latitudes, supporting previous studies [6.7]. Although
the lacustrine environment offers a unique opportunity for calibrating
MBT and CBT as it averages out small scale variability, it is not clear
yet if only pH and temperature are the driving factors. Alternativelly
the balance between the allochtonous input and in-situ production of
branched GDGTs might play an important role. Controlled growth
experiments would ultimately be needed to unravel the individual effects
of environmental parameters on the organisms producing branched GDGTs.
[1] Sinninghe Damsté J.S et al. (2000) J. Chem. Soc., Chem.
Comm., 1683-1684. [2] Weijers, J.W.H. et al. (2006) Environ. Microbiol.
8, 648-657. [3] Herfort L., et al. (2006) Limnol. Oceanogr. 51,
2196-2205. [4] Powers L.A., et al. (2004) Geology 32, 613-616. [5]
Blaga C.I., G-J. Reichart, O. Heiri, J.S. Sinninghe Damsté (2008)
J. Paleolimnol. DOI 10.1007/s10933-008-9242-2. [6] Weijers, J.W.H. et
al. (2007) Geochim. Cosmochim. Acta 71, 703-713. [7] Sinninghe
Damsté, J.S., Ossebaar, J., Schouten, S., Verschuren, D., (2008)
Org. Geochem. 39, 1072-1076.
03/2009; 11:6284.
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ABSTRACT: The phylogenetic position of diatoms belonging to the genus Attheya is presently under debate. Species belonging to this genus have been placed in the subclasses Chaetocerotophycidae and Biddulphiophycidae, but published phylogenetic trees based on 18S rDNA, morphology, and sexual reproduction indicate that this group of diatoms may be a sister group of the pennates. To clarify the position of Attheya, we studied the morphology, 18S rDNA, 16S rDNA of the chloroplasts, the rbcL large subunit (LSU) sequences of the chloroplasts, and the sterol composition of three different strains of Attheya septentrionalis (Østrup) R. M. Crawford and one strain of Attheya longicornis R. M. Crawford et C. Gardner. These data were compared with data from more than 100 other diatom species, covering the whole phylogenetic tree, with special emphasis on species belonging to the genera that have been suggested to be related to the genus Attheya. All data suggest that the investigated Attheya species form a separate group of diatoms, and there is no indication that they belong to either the Chaetocerotophycidae or the Biddulphiophycidae. Despite applying these various approaches, we were unable to determine the exact phylogenetic position of the investigated Attheya species within the diatoms.
Journal of Phycology. 01/2009; 45(2):444-453.
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ABSTRACT: Long chain 1,14-diols and 12-hydroxy methyl alkanoates are biomarker lipids for Proboscia diatoms and occur widely in Quaternary sediments. To determine the effect of temperature on the lipid composition of these algae, a new Proboscia sp. culture grown at 8á¦C and Proboscia indica cultures grown at 18, 21, 24 and 27á¦C were examined. The results were combined with lipid data from a P. indica culture and a Proboscia alata culture, grown at 20 and 2á¦C, respectively, from previous studies. The data showed a strong relationship between long chain diol and 12-hydroxy methyl alkanoate composition and growth temperature, i.e. the chain length increases and the degree of unsaturation of long chain 1,14-diols decreases with increasing growth temperature. To determine the effect of temperature on Proboscia lipid compositions in natural environments, we also analyzed fossil long chain 1,14-diols and 12-hydroxy methyl alkanoates in surface sediments derived from Proboscia diatoms living in the water column of the eastern South Atlantic. The results indicate a significant relationship between sea surface temperature and chain length distribution of saturated long chain diols, but also suggest that the relative abundances of unsaturated long chain diols and 12-hydroxy methyl alkanoates in sediments are predominantly determined by factors other than temperature
Organic Geochemistry 01/2009; 40(11):1124-1131. · 2.79 Impact Factor
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Organic Geochemistry 01/2009; 40(1):144-147. · 2.79 Impact Factor
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01/2008;
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Appl. Environ. Microbiol. 08/2007; 73:6181--6191.
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ABSTRACT: 24-norcholestanes have been shown to be useful biomarkers to assess the age of sediments and petroleum, but until now, the biological sources of their precursors, i.e., 24-norsterols, were unclear. We have unambiguously identified relatively high concentrations of 24- norcholesta-5,22-dien-3ß-ol in the diatom
Geology. 01/2007; 35(5):419-422.
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ABSTRACT: Long chain 1,14-diols and 12-hydroxy methyl alkanoates may be useful indicators for high-nutrient conditions as their inferred sources, diatoms belonging to the genus Proboscia, are often abundant in upwelling regions. In order to test this hypothesis, the lipids of three different Proboscia species in culture were determined and the fluxes of different long chain diol isomers and mid-chain hydroxy methyl alkanoates in the Arabian Sea were studied. The culture studies showed that long chain 1,14-diols and 12-hydroxy methyl alkanoates are indeed major lipids in Proboscia indica, Proboscia inermis and Proboscia alata. Time-series sediment trap data from the Arabian Sea showed increased fluxes of long chain 1,14-diols and 12-hydroxy methyl alkanoates in periods of upwelling and low fluxes for the rest of the year. High fluxes were found primarily at stations in the upwelling area close to the coast, whereas at a station located 590 km off the coast of Oman fluxes were substantially lower. These results show that long chain 1,14-diols and 12-hydroxy methyl alkanoates can be used as proxies for upwelling conditions. Flux patterns of 1,15-diols did not, however, resemble those of 1,14-diols: 1,15-diols reached maximum flux earlier than 1,14-diols, annual flux of 1,15-diols was much lower than 1,14-diols and upwelling did not seem to affect 1,15-diol flux values. This agrees with the idea that the Eustigmatophytes rather than Proboscia spp. should be considered as the major source of 1,15-diols. (c) 2006 Elsevier Ltd. All rights reserved
Organic Geochemistry 01/2007; 38(2):165-179. · 2.79 Impact Factor
